2) D

You must try and remember the reactivity series. This question is totally dependent on that.

If the element in the salt is lower down in the reactivity series compared to element it is being reacted with, a displacement reaction will occur.

1 – Al is more reactive than Pb and so will displace Pb.

2 – K is more reactive than F- and hence no displacement reaction will occur

3 – Al is more reactive than Fe so no displacement reaction will occur

4 – Zn is more reactive than Cu so a displacement reaction will occur

1 and 4 are the correct answers so option D is correct